The Spain forward spent last season on loan at Villarreal, scoring five goals in 23 appearances - including one in the Europa League semi-final first-leg win over Liverpool, a tie the Premier League side won 3-1 on aggregate.

But, after failing to find the net in nine appearances for Porto this season, Lopez has opted to head back to La Liga.

Villarreal confirmed on Saturday they had an agreement in principle with Porto.

And, after the deal was ratified, Adrian said: "I always wanted to return to Villarreal. When the possibility came up for me to come back here I told my agent to try to make it happen.

"I would have liked to have been here since the start of the season. Last year was too short for me, but it finished with three very important months for me personally and for the team, because we got to the Champions League play-offs and we fell in the semi-finals of the Europa League against a great side," he added, referring to the leg injury that sidelined him for several months.

Fran Escriba is now in charge of Villarreal after Marcelino was sacked in August, but Adrian does not envisage the change in coach being an issue.

"I will adapt very quickly because I already know everyone. There haven't been too many changes in the team," he added.